5 The role of quorum-sensing in the virulence of Pseudomonas ...

The strains highlighted with alignment in the residual 364bp were analysed to assess
if the sequence was part of a genomic island. The genomic island in C. koseri has
yet to be identified in the literature or by a database. The genomic island, if present,
did not share a conserved D flank with E. coli after an extension of 5kb in any of the
sequenced E. coli strains. The Salmonella strains all have defined and related
pathogenicity islands associated with the leuX tRNA site (Table 3-6), functionally
described as pathogencity islands containing the sefA-R chaperone-usher fimbrial
operon.
Salmonella strain Size GC% Name
Paratyphi A 31.4kb 47.20% -
CT18 32.9kb 46.60% SPI-10
Ty2 32.7kb 46.60% -
Table 3-6 Pathogencity islands defined within Salmonella strains that are leuX-associated
information gathered from Pathogenicity island database (Yoon et al. 2007)
A second SGSP amplicon was generated from the EcoRV genomic library of E. coli
E105 using the leuX D primer and the T3 universal primer. Sequencing was
performed using the KS universal primer and resulted in 750bp of DNA sequence
data. The results are depicted in Figure 3-14. Alignment of the full length sequence
(bases 1-750) to the D flank of a number of sequenced E. coli strains (≥ 97%
identity) as shown in Table 3-7.
E. coli strains Score Expected value Identity
UTI89 1315 0 98%
APEC O1 1315 0 98%
536 1315 0 98%
E24377A 1279 0 97%
Table 3-7 The highest scoring sequences from the nucleotide sequence database based on
nucleotide alignment (blastn)
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